[R] Contour plot

[Mulholland, Tom]

x <- rep(seq(1,10),10)
y <- rep(seq(1,10),each = 10)
z <- matrix(100 + x*0.5 + y*0.5,ncol=10,byrow=T)
contour(z)

or back to where you were originally


x <- 1:10
y <- 1:10
# z <- 100:110
z <- 1:100
contour(matrix(z,ncol=10))

read the help on contour it states that 
 z: a matrix containing the values to be plotted ('NA's are
          allowed).  Note that 'x' can be used instead of 'z' for
          convenience.

So 

contour(matrix(runif(100),ncol=10))

works

I can't actually say why there is an x and a y


x <- log(1:10)
y <- log(1:10)
z <- 1:100
contour(matrix(z,ncol=10))

did not do what I expected it to do. I expected the contour lines to become compressed gradually.

> -----Original Message-----
> From: dhkblaszyk at zeelandnet.nl [mailto:dhkblaszyk at zeelandnet.nl]
> Sent: Wednesday, 9 February 2005 12:44 AM
> To: r-help at stat.math.ethz.ch
> Subject: Fw: [R] Contour plot
> 
> 
> I understand that I need to have a (in this case) square 
> matrix with all the
> data. But the question now is;
> 
> - can the contourplot not interpolate the missing values

What missing values? A 10 by 10 grid is 100 possibilities, you gave 10. Which 10?

x <- 1:10
y <- 1:10
z <- matrix(numeric(100),ncol=10)
diag(z) <- 1:10
contour(z)

or 


x <- 1:10
y <- 1:10
z <- matrix(numeric(100),ncol=10)
z[trunc(runif(10) * 100)] <- 1:10
contour(z)

are two possibilities

> 
> or alternatively
> 
> - I have fit a model to the z data (z = 100 + 0.5x + 0.5y). 
> How can I make
> from this model a "square" matrix z to make a contour plot?
> 
> Kind regards, Darius Blaszijk
> 
> ----- Original Message -----
> From: "Achim Zeileis" <Achim.Zeileis at wu-wien.ac.at>
> To: <dhkblaszyk at zeelandnet.nl>
> Cc: <r-help at stat.math.ethz.ch>
> Sent: Tuesday, February 08, 2005 1:51 AM
> Subject: Re: [R] Contour plot
> 
> 
> > On Tue, 8 Feb 2005 01:15:06 +0100 dhkblaszyk at zeelandnet.nl wrote:
> >
> > > Hello,
> > >
> > > I would like to make a contourplot of the following data;
> > >
> > > > x <- 1:10
> > > > y <- 1:10
> > > > z <- 100:110
> > >
> > > By doing >contour(x,y,z) I get the following error;
> > >
> > > "Error in contour.default(x, y, z) : no proper `z' matrix 
> specified"
> > >
> > > How do I fix this??
> >
> > x and y specify a grid and thus z must provide a value for each
> > combination of the x's and y's! For example:
> >   x <- y <- 1:10
> >   contour(x, y, outer(x, y))
> > Also look at
> >   outer(x, y)
> > and read ?contour.
> >
> > Z
> >
> > > Kind regards, Datius Blaszijk
> > >
> > > [[alternative HTML version deleted]]
> > >
> > > ______________________________________________
> > > R-help at stat.math.ethz.ch mailing list
> > > https://stat.ethz.ch/mailman/listinfo/r-help
> > > PLEASE do read the posting guide!
> > > http://www.R-project.org/posting-guide.html
> > >
> 
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